include/mtd/ubi-user.h

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  12  * the GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  *
  18  * Author: Artem Bityutskiy (Битюцкий Артём)
  19  */
  20
  21 #ifndef __UBI_USER_H__
  22 #define __UBI_USER_H__
  23
  24 /*
  25  * UBI device creation (the same as MTD device attachment)
  26  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  27  *
  28  * MTD devices may be attached using %UBI_IOCATT ioctl command of the UBI
  29  * control device. The caller has to properly fill and pass
  30  * &struct ubi_attach_req object - UBI will attach the MTD device specified in
  31  * the request and return the newly created UBI device number as the ioctl
  32  * return value.
  33  *
  34  * UBI device deletion (the same as MTD device detachment)
  35  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  36  *
  37  * An UBI device maybe deleted with %UBI_IOCDET ioctl command of the UBI
  38  * control device.
  39  *
  40  * UBI volume creation
  41  * ~~~~~~~~~~~~~~~~~~~
  42  *
  43  * UBI volumes are created via the %UBI_IOCMKVOL IOCTL command of UBI character
  44  * device. A &struct ubi_mkvol_req object has to be properly filled and a
  45  * pointer to it has to be passed to the IOCTL.
  46  *
  47  * UBI volume deletion
  48  * ~~~~~~~~~~~~~~~~~~~
  49  *
  50  * To delete a volume, the %UBI_IOCRMVOL IOCTL command of the UBI character
  51  * device should be used. A pointer to the 32-bit volume ID hast to be passed
  52  * to the IOCTL.
  53  *
  54  * UBI volume re-size
  55  * ~~~~~~~~~~~~~~~~~~
  56  *
  57  * To re-size a volume, the %UBI_IOCRSVOL IOCTL command of the UBI character
  58  * device should be used. A &struct ubi_rsvol_req object has to be properly
  59  * filled and a pointer to it has to be passed to the IOCTL.
  60  *
  61  * UBI volumes re-name
  62  * ~~~~~~~~~~~~~~~~~~~
  63  *
  64  * To re-name several volumes atomically at one go, the %UBI_IOCRNVOL command
  65  * of the UBI character device should be used. A &struct ubi_rnvol_req object
  66  * has to be properly filled and a pointer to it has to be passed to the IOCTL.
  67  *
  68  * UBI volume update
  69  * ~~~~~~~~~~~~~~~~~
  70  *
  71  * Volume update should be done via the %UBI_IOCVOLUP IOCTL command of the
  72  * corresponding UBI volume character device. A pointer to a 64-bit update
  73  * size should be passed to the IOCTL. After this, UBI expects user to write
  74  * this number of bytes to the volume character device. The update is finished
  75  * when the claimed number of bytes is passed. So, the volume update sequence
  76  * is something like:
  77  *
  78  * fd = open("/dev/my_volume");
  79  * ioctl(fd, UBI_IOCVOLUP, &image_size);
  80  * write(fd, buf, image_size);
  81  * close(fd);
  82  *
  83  * Atomic eraseblock change
  84  * ~~~~~~~~~~~~~~~~~~~~~~~~
  85  *
  86  * Atomic eraseblock change operation is done via the %UBI_IOCEBCH IOCTL
  87  * command of the corresponding UBI volume character device. A pointer to
  88  * &struct ubi_leb_change_req has to be passed to the IOCTL. Then the user is
  89  * expected to write the requested amount of bytes. This is similar to the
  90  * "volume update" IOCTL.
  91  */
  92
  93 /*
  94  * When a new UBI volume or UBI device is created, users may either specify the
  95  * volume/device number they want to create or to let UBI automatically assign
  96  * the number using these constants.
  97  */
  98 #define UBI_VOL_NUM_AUTO (-1)
  99 #define UBI_DEV_NUM_AUTO (-1)
 100
 101 /* Maximum volume name length */
 102 #define UBI_MAX_VOLUME_NAME 127
 103
 104 /* IOCTL commands of UBI character devices */
 105
 106 #define UBI_IOC_MAGIC 'o'
 107
 108 /* Create an UBI volume */
 109 #define UBI_IOCMKVOL _IOW(UBI_IOC_MAGIC, 0, struct ubi_mkvol_req)
 110 /* Remove an UBI volume */
 111 #define UBI_IOCRMVOL _IOW(UBI_IOC_MAGIC, 1, int32_t)
 112 /* Re-size an UBI volume */
 113 #define UBI_IOCRSVOL _IOW(UBI_IOC_MAGIC, 2, struct ubi_rsvol_req)
 114 /* Re-name volumes */
 115 #define UBI_IOCRNVOL _IOW(UBI_IOC_MAGIC, 3, struct ubi_rnvol_req)
 116
 117 /* IOCTL commands of the UBI control character device */
 118
 119 #define UBI_CTRL_IOC_MAGIC 'o'
 120
 121 /* Attach an MTD device */
 122 #define UBI_IOCATT _IOW(UBI_CTRL_IOC_MAGIC, 64, struct ubi_attach_req)
 123 /* Detach an MTD device */
 124 #define UBI_IOCDET _IOW(UBI_CTRL_IOC_MAGIC, 65, int32_t)
 125
 126 /* IOCTL commands of UBI volume character devices */
 127
 128 #define UBI_VOL_IOC_MAGIC 'O'
 129
 130 /* Start UBI volume update */
 131 #define UBI_IOCVOLUP _IOW(UBI_VOL_IOC_MAGIC, 0, int64_t)
 132 /* An eraseblock erasure command, used for debugging, disabled by default */
 133 #define UBI_IOCEBER _IOW(UBI_VOL_IOC_MAGIC, 1, int32_t)
 134 /* An atomic eraseblock change command */
 135 #define UBI_IOCEBCH _IOW(UBI_VOL_IOC_MAGIC, 2, int32_t)
 136
 137 /* Maximum MTD device name length supported by UBI */
 138 #define MAX_UBI_MTD_NAME_LEN 127
 139
 140 /* Maximum amount of UBI volumes that can be re-named at one go */
 141 #define UBI_MAX_RNVOL 32
 142
 143 /*
 144  * UBI data type hint constants.
 145  *
 146  * UBI_LONGTERM: long-term data
 147  * UBI_SHORTTERM: short-term data
 148  * UBI_UNKNOWN: data persistence is unknown
 149  *
 150  * These constants are used when data is written to UBI volumes in order to
 151  * help the UBI wear-leveling unit to find more appropriate physical
 152  * eraseblocks.
 153  */
 154 enum {
 155         UBI_LONGTERM  = 1,
 156         UBI_SHORTTERM = 2,
 157         UBI_UNKNOWN   = 3,
 158 };
 159
 160 /*
 161  * UBI volume type constants.
 162  *
 163  * @UBI_DYNAMIC_VOLUME: dynamic volume
 164  * @UBI_STATIC_VOLUME:  static volume
 165  */
 166 enum {
 167         UBI_DYNAMIC_VOLUME = 3,
 168         UBI_STATIC_VOLUME  = 4,
 169 };
 170
 171 /**
 172  * struct ubi_attach_req - attach MTD device request.
 173  * @ubi_num: UBI device number to create
 174  * @mtd_num: MTD device number to attach
 175  * @vid_hdr_offset: VID header offset (use defaults if %0)
 176  * @padding: reserved for future, not used, has to be zeroed
 177  *
 178  * This data structure is used to specify MTD device UBI has to attach and the
 179  * parameters it has to use. The number which should be assigned to the new UBI
 180  * device is passed in @ubi_num. UBI may automatically assign the number if
 181  * @UBI_DEV_NUM_AUTO is passed. In this case, the device number is returned in
 182  * @ubi_num.
 183  *
 184  * Most applications should pass %0 in @vid_hdr_offset to make UBI use default
 185  * offset of the VID header within physical eraseblocks. The default offset is
 186  * the next min. I/O unit after the EC header. For example, it will be offset
 187  * 512 in case of a 512 bytes page NAND flash with no sub-page support. Or
 188  * it will be 512 in case of a 2KiB page NAND flash with 4 512-byte sub-pages.
 189  *
 190  * But in rare cases, if this optimizes things, the VID header may be placed to
 191  * a different offset. For example, the boot-loader might do things faster if
 192  * the VID header sits at the end of the first 2KiB NAND page with 4 sub-pages.
 193  * As the boot-loader would not normally need to read EC headers (unless it
 194  * needs UBI in RW mode), it might be faster to calculate ECC. This is weird
 195  * example, but it real-life example. So, in this example, @vid_hdr_offer would
 196  * be 2KiB-64 bytes = 1984. Note, that this position is not even 512-bytes
 197  * aligned, which is OK, as UBI is clever enough to realize this is 4th
 198  * sub-page of the first page and add needed padding.
 199  */
 200 struct ubi_attach_req {
 201         int32_t ubi_num;
 202         int32_t mtd_num;
 203         int32_t vid_hdr_offset;
 204         int8_t padding[12];
 205 };
 206
 207 /**
 208  * struct ubi_mkvol_req - volume description data structure used in
 209  *                        volume creation requests.
 210  * @vol_id: volume number
 211  * @alignment: volume alignment
 212  * @bytes: volume size in bytes
 213  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
 214  * @padding1: reserved for future, not used, has to be zeroed
 215  * @name_len: volume name length
 216  * @padding2: reserved for future, not used, has to be zeroed
 217  * @name: volume name
 218  *
 219  * This structure is used by user-space programs when creating new volumes. The
 220  * @used_bytes field is only necessary when creating static volumes.
 221  *
 222  * The @alignment field specifies the required alignment of the volume logical
 223  * eraseblock. This means, that the size of logical eraseblocks will be aligned
 224  * to this number, i.e.,
 225  *      (UBI device logical eraseblock size) mod (@alignment) = 0.
 226  *
 227  * To put it differently, the logical eraseblock of this volume may be slightly
 228  * shortened in order to make it properly aligned. The alignment has to be
 229  * multiple of the flash minimal input/output unit, or %1 to utilize the entire
 230  * available space of logical eraseblocks.
 231  *
 232  * The @alignment field may be useful, for example, when one wants to maintain
 233  * a block device on top of an UBI volume. In this case, it is desirable to fit
 234  * an integer number of blocks in logical eraseblocks of this UBI volume. With
 235  * alignment it is possible to update this volume using plane UBI volume image
 236  * BLOBs, without caring about how to properly align them.
 237  */
 238 struct ubi_mkvol_req {
 239         int32_t vol_id;
 240         int32_t alignment;
 241         int64_t bytes;
 242         int8_t vol_type;
 243         int8_t padding1;
 244         int16_t name_len;
 245         int8_t padding2[4];
 246         char name[UBI_MAX_VOLUME_NAME + 1];
 247 } __attribute__ ((packed));
 248
 249 /**
 250  * struct ubi_rsvol_req - a data structure used in volume re-size requests.
 251  * @vol_id: ID of the volume to re-size
 252  * @bytes: new size of the volume in bytes
 253  *
 254  * Re-sizing is possible for both dynamic and static volumes. But while dynamic
 255  * volumes may be re-sized arbitrarily, static volumes cannot be made to be
 256  * smaller then the number of bytes they bear. To arbitrarily shrink a static
 257  * volume, it must be wiped out first (by means of volume update operation with
 258  * zero number of bytes).
 259  */
 260 struct ubi_rsvol_req {
 261         int64_t bytes;
 262         int32_t vol_id;
 263 } __attribute__ ((packed));
 264
 265 /**
 266  * struct ubi_rnvol_req - volumes re-name request.
 267  * @count: count of volumes to re-name
 268  * @padding1:  reserved for future, not used, has to be zeroed
 269  * @vol_id: ID of the volume to re-name
 270  * @name_len: name length
 271  * @padding2:  reserved for future, not used, has to be zeroed
 272  * @name: new volume name
 273  *
 274  * UBI allows to re-name up to %32 volumes at one go. The count of volumes to
 275  * re-name is specified in the @count field. The ID of the volumes to re-name
 276  * and the new names are specified in the @vol_id and @name fields.
 277  *
 278  * The UBI volume re-name operation is atomic, which means that should power cut
 279  * happen, the volumes will have either old name or new name. So the possible
 280  * use-cases of this command is atomic upgrade. Indeed, to upgrade, say, volumes
 281  * A and B one may create temporary volumes %A1 and %B1 with the new contents,
 282  * then atomically re-name A1->A and B1->B, in which case old %A and %B will
 283  * be removed.
 284  *
 285  * If it is not desirable to remove old A and B, the re-name request has to
 286  * contain 4 entries: A1->A, A->A1, B1->B, B->B1, in which case old A1 and B1
 287  * become A and B, and old A and B will become A1 and B1.
 288  *
 289  * It is also OK to request: A1->A, A1->X, B1->B, B->Y, in which case old A1
 290  * and B1 become A and B, and old A and B become X and Y.
 291  *
 292  * In other words, in case of re-naming into an existing volume name, the
 293  * existing volume is removed, unless it is re-named as well at the same
 294  * re-name request.
 295  */
 296 struct ubi_rnvol_req {
 297         int32_t count;
 298         int8_t padding1[12];
 299         struct {
 300                 int32_t vol_id;
 301                 int16_t name_len;
 302                 int8_t  padding2[2];
 303                 char    name[UBI_MAX_VOLUME_NAME + 1];
 304         } ents[UBI_MAX_RNVOL];
 305 } __attribute__ ((packed));
 306
 307 /**
 308  * struct ubi_leb_change_req - a data structure used in atomic logical
 309  *                             eraseblock change requests.
 310  * @lnum: logical eraseblock number to change
 311  * @bytes: how many bytes will be written to the logical eraseblock
 312  * @dtype: data type (%UBI_LONGTERM, %UBI_SHORTTERM, %UBI_UNKNOWN)
 313  * @padding: reserved for future, not used, has to be zeroed
 314  */
 315 struct ubi_leb_change_req {
 316         int32_t lnum;
 317         int32_t bytes;
 318         int8_t  dtype;
 319         int8_t  padding[7];
 320 } __attribute__ ((packed));
 321
 322 #endif /* __UBI_USER_H__ */